Ambulatory infusion devices and filter assemblies for use with same

ABSTRACT

An ambulatory infusing device including a housing, a reservoir defining an interior volume, a wall associated with the housing and having an inner surface that faces into the reservoir interior volume, and a filter assembly. The filter assembly may include a filter assembly housing with a housing filter portion having a free end associated with the inner surface of the wall and a filter supporting volume that extends to the free end of the housing filter portion, and a filter located within the filter supporting volume that extends to at least the free end of the housing filter portion.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application No.62/452,637, filed Jan. 31, 2017, which is incorporated herein byreference.

BACKGROUND OF THE INVENTIONS 1. Field of Inventions

The present inventions relate generally to ambulatory infusion devices.

2. Description of the Related Art

Ambulatory infusion devices, such as implantable infusion devices andexternally carried infusion devices, have been used to provide a patientwith a medication or other substance (collectively “infusiblesubstance”) in accordance with a delivery profile that specifies one ormore flow rates during the delivery profile cycle, and frequentlyinclude a reservoir and a fluid transfer device. The reservoir is usedto store the infusible substance and is coupled to the fluid transferdevice which is, in turn, connected to an outlet port. A catheter, whichhas at least one outlet at the target body region, may be connected tothe outlet port. As such, infusible substance in the reservoir may betransferred from the reservoir to the target body region by way of thefluid transfer device and catheter.

SUMMARY

An infusion device in accordance with at least one of the presentinventions includes a housing, a reservoir defining an interior volume,a wall associated with the housing and having an inner surface thatfaces into the reservoir interior volume, and a filter assembly. Thefilter assembly may include a filter assembly housing with a housingfilter portion having a free end associated with the inner surface ofthe wall and a filter supporting volume that extends to the free end ofthe housing filter portion, and a filter located within the filtersupporting volume that extends to at least the free end of the housingfilter portion. There are a variety of advantages associated with suchan infusion device. By way of example, but not limitation, a filter thatextends to at least the free end of the housing filter portioneliminates the above-described bubble trap. As such, the infusion devicewill be functionally effective when there are air bubbles in theinfusible substance.

BRIEF DESCRIPTION OF THE DRAWINGS

Detailed descriptions of exemplary embodiments will be made withreference to the accompanying drawings.

FIG. 1 is a front view of an implantable infusion device.

FIG. 2 is a partial section view taken along line 2-2 in FIG. 1.

FIG. 3 is perspective view of the filter assembly in the implantableinfusion device illustrated in FIG. 1.

FIG. 4 is a section view of a portion of the implantable infusion deviceillustrated in FIG. 1.

FIG. 5 is a front view of an implantable infusion device in accordancewith one embodiment of a present invention.

FIG. 6 is a front view of the implantable infusion device illustrated inFIG. 5 with the housing cover removed.

FIG. 7 is a side, partial section view of a portion of the implantableinfusion device illustrated in FIG. 5.

FIG. 8 is a block diagram of the implantable infusion device illustratedin FIG. 5.

FIG. 9 is a rear, cutaway view of the implantable infusion deviceillustrated in FIG. 5 with the housing bottom portion removed.

FIG. 10 is a perspective view of the filter assembly in the implantableinfusion device illustrated in FIG. 5.

FIG. 11 is an exploded perspective view of the filter assembly in theimplantable infusion device illustrated in FIG. 5.

FIG. 12 is a section view of a portion of the implantable infusiondevice illustrated in FIG. 5.

FIG. 13 is a section view of a portion of an implantable infusion devicein accordance with one embodiment of a present invention.

FIG. 14 is a section view of a portion of an implantable infusion devicein accordance with one embodiment of a present invention.

FIG. 15 is a section view of a portion of an implantable infusion devicein accordance with one embodiment of a present invention.

FIG. 16 is a section view of a portion of an implantable infusion devicein accordance with one embodiment of a present invention.

FIG. 17 is a section view of a portion of an implantable infusion devicein accordance with one embodiment of a present invention.

FIG. 18 is a section view of a portion of an implantable infusion devicein accordance with one embodiment of a present invention.

FIG. 19 is a perspective view of a filter in accordance with oneembodiment of a present invention.

FIG. 20 is a perspective view of a filter in accordance with oneembodiment of a present invention.

FIG. 21 is a section view taken along line 21-21 in FIG. 20.

FIG. 22 is a perspective view of a filter in accordance with oneembodiment of a present invention.

FIG. 23 is a section view taken along line 23-23 in FIG. 22.

FIG. 24 is a perspective view of a filter in accordance with oneembodiment of a present invention.

FIG. 25 is a section view taken along line 25-25 in FIG. 24.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

The following is a detailed description of the best presently knownmodes of carrying out the inventions. This description is not to betaken in a limiting sense, but is made merely for the purpose ofillustrating the general principles of the inventions. The presentinventions have application in a wide variety of apparatus. One exampleis an electromagnet-pump-based fluid transfer device that may beemployed in an implantable infusion device. The present inventions arenot, however, limited to electromagnet-pump-based fluid transfer devicesand implantable infusion devices and are instead also applicable toother fluid transfer devices and infusion devices that currently exist,or are yet to be developed. For example, the present inventions areapplicable to fluid transfer devices with solenoid pumps or any otherpump that delivers a known and non-adjustable volume into a compliantvolume.

One example of an infusion device is illustrated in FIGS. 1 and 2. Theinfusion device 10 includes a housing 12 (e.g. a titanium housing) witha bottom portion 14, an internal wall 16, and a cover 18. A reservoir 20is located within the housing bottom portion 14 and an infusiblesubstance (e.g. medication) may be stored in the reservoir internalvolume 22. A wide variety of reservoirs may be employed. In theillustrated embodiment, the reservoir 20 is in the form of a titaniumbellows, with convolutes 23 and an end wall 24, that is positionedwithin a sealed volume defined by the housing bottom portion 14 andinternal wall 16. The remainder of the sealed volume is occupied bypropellant P, which may be used to exert negative pressure on thereservoir 20. The reservoir 20 may be replenished by way of a fill port26 that extends through the housing cover 18 and is connected to areservoir inlet 28. A hypodermic needle (not shown), which is configuredto be pushed through the fill port 26, may be used to replenish thereservoir 20. A safety valve (not shown) that is configured to closewhen the pressure within the internal volume 22 reaches a predeterminedlevel may be located between the fill port 26 and the reservoir inlet28. The fluid transfer device and various electronic components (notshown) are located within a sealed volume defined by the housinginternal wall 16 and cover 18. The inlet of the fluid transfer device iscoupled to the reservoir internal volume 22 by way of a filter assembly30 that blocks pathogens and precipitates which may be in the infusiblesubstance. The outlet of the fluid transfer device is operably connectedto a catheter 32. Access to the catheter 32 may also be obtained by wayof a catheter access port 34.

Turning to FIGS. 3 and 4, the filter assembly 30 includes a housing 36and a filter 38 having a bacterial filtration element 40 and aperforated support disk 42 that prevents distortion of the filterelement. The filtration element 40 may be a pathogen-blocking bacterialfiltration element formed from hydrophilic material that does not passnon-water based liquids or gas. The housing 36 includes a filter portion44, with a recess 46 for the filter 38, and a connector portion 48 withan outlet lumen 50 that is operably connected to the inlet of the fluidtransfer device. A lumen 52 extends from the recess 46 to the outletlumen 50. The outer perimeter of the filter 38 (i.e., the outerperimeters of the filtration element 40 and support disk 42) iscompressed between a support ring 54 and an annular abutment 56 withinthe recess 46. The support ring 54 may be welded or otherwise secured tothe housing filter portion 44.

The internal wall 16 includes an aperture 58 in which the housing filterportion 44 is mounted. The internal wall 16 also includes a recess 60for the similarly-shaped filter flange 62, which together ensure thatthat filter housing connector portion 48 is in its intended locationwithin the sealed volume defined by the housing internal wall 16 andcover 18. The respective sizes and configurations of the internal wall16 and the filter housing 36 results in the free end 64 of the filterhousing being flush with the inner surface 66 of the wall 16. Operationof the fluid transfer device causes infusible substance IF within thereservoir internal volume 22 to be draw through the filter 38, recess46, and lumens 50 and 52, and then into the fluid transfer device inlet.The reservoir convolutes 23 will compress, and the reservoir end wall 24will move toward the internal wall 16, as the infusible substance isevacuated from the reservoir 20 and the internal volume 22 shrinks.

Although useful, the present inventors have determined that infusiondevice 10 is susceptible to improvement. One issue is associated withgas bubbles within the reservoir 20 and the configuration of the filterassembly 30. In particular, many infusible substances contain dissolvedgases that may evolve from solution and, due to gravity, accumulate andform a bubble at the top region of the reservoir. The region of thereservoir that defines the “top” region will vary based on theorientation of the patient (i.e., standing, sitting, lying down, etc.).With respect to the configuration of the filter assembly 30, andreferring to FIGS. 3 and 4, the respective sizes and configurations ofthe filter housing 36 and filter 38 are such that there is an open,unfilled disk-shaped space (or “pocket”) 68 that faces the reservoirinternal volume 22. The depth D1 of the pocket 68 is equal to the depthD2 of the portion of the housing recess 46 that extends from the annularabutment 56 to the free end 64, less the thickness of the filter 38. Putanother way, the depth D1 of the pocket 68 is equal to distance betweenthe surface of the filter 38 that faces the reservoir and the free end64 of the housing filter portion 44. The pocket 68 can act as a bubbletrap which, as a result of the typical orientation of the infusiondevice 10 within the patient, will define the highest point within thereservoir when the patient is in a supine position.

The presence of a gas bubble within the pocket 68 and over the filter 38is problematic because the hydrophilic filter element 40 will be blockedby the bubble. Even a microscopic gas bubble is capable of thinning out,spreading across the entire surface of the wetted filter, therebypreventing the infusible substance from reaching the fluid transferdevice. Depending upon the volume of the bubble and negative pressuregenerated by the pump, the bubble may cover the surface of the supportdisk 42, and/or fill the perforations of the support disk, and/or or getbetween the bacterial filtration element 40 and the support disk andcover the reservoir-facing surface of the filtration element. In thoseinstances where the fluid transfer is capable of generating enough forceto draw a bubble through the filter 38, certain types of fluid transferdevices (e.g., electromagnet pumps) will experience vapor lock.Moreover, given the depth of the pocket 68 and other factors (e.g.,surface tension), the bubble may not float out of the pocket in responseto movement and/or reorientation of the patient.

There are also other instances, based on patient orientation andreservoir volume, where the bubble may enter the filter assembly pocket68. For example, the liquid volume to bubble volume ratio will berelatively large, and the bubble will tend to remain within the bellowsconvolutes 23, when the reservoir is relatively full (FIG. 2). As thereservoir 20 is depleted, the bubble may be squeezed out of reservoirconvolutes 23, and towards the filter assembly 30. A bubble may alsosimply migrate along the inner surface 66 of the wall 16 toward thefilter assembly 30, regardless of reservoir volume, in response tochanges in patient (and infusion device) orientation. The presentinventors have determined that, in either case, the fact that the freeend 64 of the filter housing 44 is flush with the inner surface 66 ofthe wall 16 increases the likelihood that the bubble will enter thepocket 68.

One example of an implantable infusion device in accordance with atleast some of the present inventions is generally represented byreference numeral 100 in FIGS. 5-8. As used herein, an “implantableinfusion device” is a device that includes a reservoir and an outlet,and is sized, shaped and otherwise constructed (e.g. sealed) such thatboth the reservoir and outlet can be simultaneously carried within thepatient's body. The exemplary infusion device 100 includes a housing 102(e.g. a titanium housing) with a bottom portion 104, a divider wall 106,and a cover 108. An infusible substance (e.g. medication) may be storedin a reservoir 110 that is located within the housing bottom portion104. The reservoir 110 may be replenished by way of a fill port 112 thatextends from the reservoir, through the divider wall 106, to the cover108. A hypodermic needle (not shown), which is configured to be pushedthrough the fill port 112, may be used to replenish the reservoir 110.An inlet side safety valve 114, closes when the pressure within thereservoir reaches a predetermined level, may be located betweenreservoir 110 and the fill port 112.

A wide variety of reservoirs may be employed. In the illustratedembodiment, the reservoir 110 is in the form of a titanium bellows withconvolutes 116 and an end wall 118 that is positioned within a sealedvolume 120 defined by the housing bottom portion 104 and divider wall106. The remainder of the sealed volume is occupied by propellant (notshown), which may be used to exert negative pressure on the reservoir110. Other reservoirs that may be employed in the present infusiondevices include reservoirs in which propellant exerts a positivepressure. Still other exemplary reservoirs include negative pressurereservoirs that employ a movable wall that is exposed to ambientpressure and is configured to exert a force that produces an interiorpressure which is always negative with respect to the ambient pressure.

The exemplary ambulatory infusion device 100 illustrated in FIGS. 5-8also includes a fluid transfer device 122 which, in the illustratedimplementation, is an electromagnet-pump-based fluid transfer device.Although the present inventions are not so limited, various examples ofsuitable fluid transfer devices are illustrated and described in U.S.Pat. No. 8,740,861, which is incorporated by reference. The inlet of thefluid transfer device 122 is coupled to the interior 124 (FIGS. 9 and12) of the reservoir 110 by a filter assembly 126 that is connected toan inlet tube associated with the fluid transfer device 122. The outletof the fluid transfer device is coupled to an outlet port 128 by apassageway 130 that defines a path from the fluid transfer device to theoutlet port. Operation of the fluid transfer device 100 causes infusiblesubstance to move from the reservoir 110 to the infusion device outletport 128. A catheter 132 may be connected to the outlet port 128 so thatthe infusible substance passing through the outlet port will bedelivered to a target body region in spaced relation to the infusiondevice 100 by way of the outlet(s) 134 at or near the end of thecatheter.

Energy for the fluid transfer device 122, as well for other aspects ofthe exemplary infusion device 100, is provided by the battery 136illustrated in FIG. 6. In the specific case of the fluid transfer device100, the battery 136 is used to charge one or more capacitors 138, andis not directly connected to the fluid transfer device itself. Thecapacitor(s) 138 are connected to an electromagnet coil in the fluidtransfer device 122, and disconnected from the battery 136, when theelectromagnet coil is being energized, and are disconnected from theelectromagnet coil and connected to the battery when the capacitor(s)are being recharged and/or when the fluid transfer device is at rest.The capacitor(s) 138 are carried on a board 140. A communication device142, which is connected to an antenna (not shown), is carried on thesame side of the board 140 as the capacitor(s) 138. The exemplarycommunication device 142 is an RF communication device. Other suitablecommunication devices include, but are not limited to, oscillatingmagnetic field communication devices, static magnetic fieldcommunication devices, optical communication devices, ultrasoundcommunication devices and direct electrical communication devices.

A controller 144 (FIG. 8), such as a microprocessor, microcontroller orother control circuitry, is carried on the other side of the board 140.The controller 144 performs the function of controlling the operationsof the infusion device 100 in accordance with instructions stored inmemory 145 and/or provided by an external device (e.g. a remote controlprogrammer) by way of the communication device 142. For example, thecontroller 144 may be used to control the fluid transfer device 122 tosupply fluid to the patient in accordance with, for example, a storedbasal delivery profile or a bolus delivery request. The controller 144may also be used to monitor sensed pressure and to perform variousanalytical and corrective functions.

Referring to FIGS. 5, 6 and 8, the exemplary infusion device 100 is alsoprovided with a side port 146 that is connected to the passageway 130between the outlet of the fluid transfer device 122 and the outlet port128. The side port 146 facilitates access to an implanted catheter 132,typically by way of a hypodermic needle. The outlet port 128, a portionof the passageway 130, the antenna (not shown) and the side port 146 arecarried by a header assembly 148. The header assembly 148 is a molded,plastic structure that is secured to the housing 102.

The exemplary infusion device 100 illustrated in FIGS. 5-8 also includesa pressure sensor 150 that is connected to the passageway 130 betweenthe outlet of the fluid transfer device 122 and the outlet port 128. Thepressure sensor 150 is connected to the controller 144 and may be usedto analyze a variety of aspects of the operation of the exemplaryimplantable infusion device 100. For example, pressure measurements maybe used by the controller 144 to determine whether or not there is ablockage in the catheter 132 and whether or not the fluid transferdevice 122 is functioning properly. The controller 144 may perform avariety of different functions in response to a determination that thefluid transfer device 122 is not functioning properly or a determinationthat the catheter 132 is blocked. For example, the controller 144 mayactuate an audible alarm 152 that is located within the housing 102 inorder to signal that the fluid transfer device 122 is not functioningproperly or the catheter 132 is blocked. The controller 144 may also beused to determine, based on the pressure sensed by the pressure sensor150, whether there is a blockage.

Turning to FIGS. 9-12, the exemplary filter assembly 126 includes ahousing 154 and a filter 156 having a hydrophilic bacterial filterelement 158 and a perforated support disk 160 (or other liquid permeablefilter support) that prevents distortion of the filter element. Suitablematerials for the filter element 158 and other filter elements discussedherein include, but are not limited to polysulfone, polyvinylidenefluoride, and cellulose with a thickness of about 125 μm to 200 μm,while suitable materials for the perforated disk 160 and otherperforated disks discussed herein include, but are not limited totitanium, stainless steel, polysulfone with a thickness of about 0.1 mmto 5 mm. The disk perforations 161, which extend completely through thedisk 160, may be about 0.01 mm to 1 mm in diameter. The perforated disk160 may be secured to the housing by press fitting, welding, or anyother suitable process or instrumentality. Other exemplary filters aredescribed below with reference to FIGS. 13-25.

The exemplary housing 154 includes a filter portion 162, with a recess164 for the filter 156, and a connector portion 166 with an outlet lumen168 that is operably connected to the inlet of the fluid transfer device122. A lumen 170 extends from the recess 164 to the outlet lumen 168.The support disk 160 is pressed into the filter recess of the housing154, and the outer perimeter of the filter element 158 is compressedbetween the outer perimeter of the support disk and an annular abutment172 within the recess 164. The divider wall 106 includes an aperture 174in which the housing filter portion 162 is mounted as well as a recess176 for the similarly-shaped filter flange 178, which together ensurethat that filter housing connector portion 166 is in its intendedlocation adjacent to the inlet of the fluid transfer device 122.

Referring more specifically to FIG. 12, the thickness T of the exemplaryfilter 156 (i.e., the combined thickness of the filter element 158 andperforated support disk 160) may be at least equal to the depth D2 ofthe portion of the housing recess 164 that extends from the annularabutment 172 to the housing filter portion free end 180 and defines thefilter supporting volume. The filter 158, at a minimum, occupies theentire volume of the portion of the housing recess 164 that extends fromthe annular abutment 172 to the free end 180. As a result, the filterassembly 126 does not have a pocket similar to the pocket 68 of thefilter assembly 30 (FIGS. 3 and 4) that can act as a bubble trap. In theillustrated implementation, the thickness T is slightly greater than thedepth D2, but the thickness T can be the same as the depth D2 in otherimplementations.

It should also be noted that the free end 180 of the housing filterportion 162 is not flush with the inner surface 182 of the divider wall106 in the illustrated implementation. The free end 180 is insteadoffset the inner surface 182, which faces and defines a border of thereservoir interior 124, by a distance D3 of about 0.1 mm to 1.0 mm andprojects into the reservoir interior by the distance D3. The part of thehousing filter portion 162 that extends beyond the inner surface 182acts as a barrier, or fence, that will impede a bubble within thereservoir interior that is moving along the inner surface of the dividerwall 106 prior to the bubble reaching the filter 156.

Turning to FIG. 9, the filter assembly 126 is not located adjacent tothe reservoir convolutes 116. As such, a bubble squeezed out ofreservoir convolutes 116 and towards the filter assembly 126, as thereservoir interior 124 is depleted, will be less likely to reach thefilter assembly and cover the filter 156. The inner surface 182 of thedivider wall 106 may also include one or more channels, such as channels185 and 187, which prevent the bellows end wall 118 from sticking to thedivider wall 106 when the reservoir is empty.

Another exemplary filter assembly is generally represented by referencenumeral 126 a in FIG. 13. The exemplary filter assembly 126 a issubstantially similar to filter assembly 126 and similar elements arerepresented by similar reference numerals. For example, the filterassembly 126 a may be incorporated into the exemplary infusion device100 in place of the filter assembly 126. The filter includes a filterelement 158 and a support disk 160 a. The filter 156 a also occupies (ata minimum) the entire portion of the housing recess 164 that extendsfrom the annular abutment 172 to the free end 180 and, as a result, thefilter assembly 126 a does not have a bubble-trapping pocket similar tothe pocket 68 of the filter assembly 30 (FIGS. 3 and 4).

Here, however, the end surface 183 a of the exemplary filter 156 a thatfaces the reservoir interior 124 is configured such that the centralregion 184 a of the end surface extends farther than the outer perimeterregion 186 a of the end surface. Put another way, the end surfacecentral region 184 a is closer to the bellows end wall 118 than is theend surface outer perimeter 186 a. As a result, the portion of the endsurface 183 a through which the perforations 161 extend will not be thehigh point within the reservoir 110 when the infusion device is theorientation illustrated in FIG. 13, and the bubble will be less likelyto come to rest over the perforations. The filter end surface 183 a,which is the end surface support disk 160 a in the illustratedembodiment, may have convex shape (as shown), a conical shape, or anyother suitable symmetric or asymmetric shape. Additionally, although thepoint of greatest extension is at the center of the end surface 183 a,the point of greatest extension may also be offset from the center inother implementations.

Turning to FIG. 14, the exemplary filter assembly 126 b is substantiallysimilar to filter assembly 126 and similar elements are represented bysimilar reference numerals. For example, the filter assembly 126 b maybe incorporated into the exemplary infusion device 100 in place of thefilter assembly 126. The filter 156 b, which includes a filter element158 b and a perforated support disk 160 b, also occupies (at least) theentire portion of the housing recess 164 that extends from the annularabutment 172 to the free end 180 and, as a result, the filter assembly126 b does not have a bubble-trapping pocket similar to the pocket 68 ofthe filter assembly 30 (FIGS. 3 and 4).

Here, however, the filter support disk support disk 160 b includes anannular flange 188 b that is aligned with the annular abutment 172. Theouter perimeter of the filter 156 b (i.e., the outer perimeter of thefiltration element 158 and the annular flange 188 b) is compressedbetween a support ring 190 b and the annular abutment 172. The supportring 190 b may be welded, press-fit, or otherwise secured to the housingfilter portion 162. It should also be noted that the filter end surface183 b, which is the end surface support disk 160 b in the illustratedembodiment, may be flat (as shown) or may have convex shape, a conicalshape, or any other suitable shape.

Although some filters, such as the exemplary filters described abovewith reference to FIGS. 9-14, may include separate filter elements andperforated support disks that are placed adjacent to one another duringassembly of the associated filter assembly, the present inventions arenot so limited. To that end, and referring to FIG. 15, the exemplaryfilter assembly 126 c is substantially similar to filter assembly 126and similar elements are represented by similar reference numerals. Forexample, the filter assembly 126 c may be incorporated into theexemplary infusion device 100 in place of the filter assembly 126. Thefilter 156 c also occupies (at least) the entire portion of the housingrecess 164 that extends from the annular abutment 172 to the free end180 and, as a result, the filter assembly 126 b does not have abubble-trapping pocket similar to the pocket 68 of the filter assembly30 (FIGS. 3 and 4).

Here, however, the filter 156 c is an integrated, unitary structure thatconsists of a hydrophilic membrane that is laminated to one or morelayers of support material. Exemplary hydrophilic membrane may be formedfrom materials such as polysulfone, while exemplary support materialsinclude woven or non-woven polypropylenes and polyesters or a calenderedsupport. The filter end surface 183 c may be flat (as shown) or may haveconvex shape, a conical shape, or any other suitable shape. The outerperimeter of the filter 156 c is compressed between a support ring 190 cand the annular abutment 172. The support ring 190 c, may be welded,press-fit, or otherwise secured to the housing filter portion 162,includes an outer portion 192 c and a flange 194 c that extends inwardlyfrom the outer portion.

The exemplary filter assembly generally represented by reference numeral126 d in FIG. 16 is substantially similar to filter assembly 126 andsimilar elements are represented by similar reference numerals. Forexample, the filter assembly 126 d may be incorporated into theexemplary infusion device 100 in place of the filter assembly 126. Thefilter 156 d also occupies (at least) the entire portion of the housingrecess 164 that extends from the annular abutment 172 to the free end180 and, as a result, the filter assembly 126 d does not have abubble-trapping pocket similar to the pocket 68 of the filter assembly30 (FIGS. 3 and 4).

Here, however, the filter 156 d includes a filter element 158, arelatively thin support disk 160 d, and a liquid absorbent member 196 d.The liquid absorbent member 196 d stores the infusible substance. Inthose instances where the exposed surface of the filter assembly 126 dis completely covered by a bubble, i.e., when the liquid absorbentmember 196 d is covered by a bubble, the infusible substance stored inthe liquid absorbent member will be drawn through the filter element 158and support disk 160 d, and into the fluid transfer device 122. Suitablematerials for the liquid absorbent member 196 d include, but are notlimited to hydrophilic sponge materials, polyurethane, and cellulose.

The filter end surface 183 d (which is the end surface of the liquidabsorbent member 196 d) may be flat or may have convex shape (as shown),a conical shape, or any other suitable shape. The outer perimeter of thefilter 156 d is compressed between a support ring 190 d and the annularabutment 172. The support ring 190 d may be welded, press-fit, orotherwise secured to the housing filter portion 162. In some instances,the outer perimeter of the liquid absorbent member 196 d may include athin flange that is compressed between the support ring 190 d and theannular abutment 172.

It should also be noted that, in some instances, the free end of thehousing filter portion may simply be flush with the inner surface of thedivider wall. To that end, and referring to FIG. 17, the relativedimensions of the divider wall 106′ and the filter assembly 126 b aresuch that the free end 180 of the housing filter portion 162 is flushwith the divider wall inner surface 182.

Another exemplary filter assembly is generally represented by referencenumeral 126 e in FIG. 18. Filter assembly 126 e is substantially similarto filter assembly 126 a and similar elements are represented by similarreference numerals. For example, the filter assembly 126 e may beincorporated into the exemplary infusion device 100 in place of thefilter assembly 126. The filter 156 e occupies (at least) the entireportion of the housing recess 164 that extends from the annular abutment172 to the free end 180 and, as a result, the filter assembly 126 e doesnot have a bubble-trapping pocket similar to the pocket 68 of the filterassembly 30 (FIGS. 3 and 4). The filter 156 e may also have the endsurface 183 e that faces the reservoir interior 124 is configured suchthat the central region 184 e extends farther than the outer perimeterregion 186 e (as shown) or may have a flat end surface. The end surface183 e may have convex shape (as shown), a conical shape, or any othersuitable symmetric or asymmetric shape.

Here, however, the filter 156 e is one-piece, unitary structure that isformed from porous sintered titanium (or other porous sintered metal).The filter 156 e has an absolute filter rating (or “filter rating”) of0.2 μm in the illustrated implementation, i.e., the filter will blockparticles that are 0.2 μm or larger. The filter rating is consistentthroughout the filter 156 e. In other implementations, the filter ratingmay vary from the end surface 183 e to the opposite surface and/or fromthe central region 184 e to the outer perimeter region 186 e. To thatend, the exemplary filter 156 f, which may be used in place of thefilter 156 e in the filter assembly 126 e, includes a first filter layer156 f-1 with a filter rating of 0.2 μm and a second filter layer 156 f-2with a filter rating of 2.0 μm. In other implementations, the filterrating variation may be gradual over the entire thickness, as opposed tothe use of two distinct layers having different filter ratings.

The sintered titanium filters 156 e and 156 f illustrated in FIGS. 18-21have smooth (but for the pores) reservoir facing surfaces 183 e and 183f. Other filter implementations, which may be used in place of thefilter 156 e in the filter assembly 126 e, include surface features thatdecrease the likelihood that a bubble which reaches the reservoir facingsurface will conform to the entire surface and block the filter. By wayof example, but not limitation, the filter 156 g (FIGS. 22 and 23)includes a plurality of apertures 198 g that extend through the surface183 g, while the filter 156 h (FIGS. 24 and 25) includes a plurality ofslots 198 h that extend through the surface 183 h. The apertures 198 gand slots 198 h extend only partially through the filters 156 g and 156h.

The filters 156 e to 156 h may be secured to the housing 154 by, forexample, press fitting and/or laser welding, and in many instanceswithout the use of a support ring. With respect to manufacturing, thefilters 156 e to 156 h may be formed by known sintering processes, suchas mold-based sintering and selective laser sintering. Surface featuressuch as the apertures 198 g and slots 198 h may also be formed in asmooth sintered filter (such as that illustrated in FIGS. 18 and 19)through the use of laser engraving or other suitable techniques.

Although the inventions disclosed herein have been described in terms ofthe preferred embodiments above, numerous modifications and/or additionsto the above-described preferred embodiments would be readily apparentto one skilled in the art. By way of example, but not limitation, thepresent inventions have application in infusion devices that includemultiple reservoirs and/or outlets. Moreover, the inventions include anyand all combinations of the elements from the various embodimentsdisclosed in the specification. It is intended that the scope of thepresent inventions extend to all such modifications and/or additions andthat the scope of the present inventions is limited solely by the claimsset forth below.

We claim:
 1. An ambulatory infusing device, comprising: a housing; areservoir defining an interior volume; a wall associated with thehousing and having a wall inner surface that faces into the reservoirinterior volume; and a filter assembly including a filter assemblyhousing with a housing filter portion having a free end associated withthe wall inner surface, a housing filter portion inner surface and afilter supporting volume that extends to the free end of the housingfilter portion and to the housing filter portion inner surface, and afilter that occupies the entire filter supporting volume that extends toat least the free end of the housing filter portion and to the housingfilter portion inner surface.
 2. An ambulatory infusing device asclaimed in claim 1, wherein the filter comprises a filter element and aliquid permeable filter support.
 3. An ambulatory infusing device asclaimed in claim 2, wherein the filter element comprises a hydrophilicmembrane.
 4. An ambulatory infusing device as claimed in claim 2,wherein the liquid permeable filter support comprises a perforated disk.5. An ambulatory infusing device as claimed in claim 2, wherein thefilter element is laminated to the liquid permeable filter support. 6.An ambulatory infusing device as claimed in claim 2, wherein the filterincludes a liquid absorbent member.
 7. An ambulatory infusing device asclaimed in claim 1, wherein the filter comprises a hydrophilic membranethat is laminated to one or more layers of support material.
 8. Anambulatory infusing device as claimed in claim 1, wherein the filtercomprises a sintered metal filter.
 9. An ambulatory infusing device asclaimed in claim 8, wherein the metal comprises titanium.
 10. Anambulatory infusing device as claimed in claim 8, wherein the sinteredmetal filter includes a plurality of surface features that extendpartially through the filter.
 11. An ambulatory infusing device asclaimed in claim 8, wherein different portions of the sintered metalfilter define different filter ratings.
 12. An ambulatory infusingdevice as claimed in claim 1, wherein the filter defines an end surface,including a central region and an outer perimeter region, that faces thereservoir interior volume and the central region of the end surfaceextends farther than the outer perimeter region of the end surface intothe reservoir interior volume.
 13. An ambulatory infusing device asclaimed in claim 1, wherein the filter defines a flat end surface thatfaces the reservoir interior volume.
 14. An ambulatory infusing deviceas claimed in claim 1, wherein the free end of the filter assemblyhousing filter portion extends beyond the wall inner surface.
 15. Anambulatory infusing device as claimed in claim 1, wherein the free endof the filter assembly housing filter portion is flush with the wallinner surface.
 16. An ambulatory infusing device as claimed in claim 1,wherein the reservoir comprises a bellows reservoir.
 17. An ambulatoryinfusing device as claimed in claim 1, further comprising: a fluidtransfer device operably connected to the reservoir interior volume byway of the filter assembly.
 18. An ambulatory infusing device as claimedin claim 17, wherein the fluid transfer device comprises anelectromagnet pump-based fluid transfer device.